A vehicle using an internal combustion engine using gasoline or heavy oil as main fuel has a serious effect on pollutions such as air pollution. Therefore, in order to reduce the pollutants, many attempts to develop an electric vehicle or a hybrid electric vehicle have been recently conducted.
Recently, a high output secondary battery using a high energy density non-aqueous electrolyte has been developed. A plurality of high output secondary batteries are connected to each other in series so as to be able to be used in equipment requiring large power for driving a motor such as the electric vehicle, and the like, thereby configuring a large-capacity secondary battery.
As such, a single large-capacity secondary battery is referred to as ‘battery cell’, and a plurality of battery cells are connected to each other in series or in parallel to form a battery module. After the battery module is completed by forming the plurality of battery cells in the module structure and then additionally assembling a voltage measurement means for measuring voltages of the battery cells and other parts. In this case, the battery cells are provided with electrode tabs to electrically connect the plurality of battery cells, in which the plurality of battery cells are connected by various methods such as clip, compression, welding, and bolting. Further, the voltage measurement means and other parts are additionally assembled around the electrode tabs.
However, the typical battery module may be instable against vibrations and external shocks due to the assembling of the voltage measurement means and other parts and may not implement easy welding due to a difference in materials between the electrode tab and the voltage measurement means. Therefore, the operation of the battery module may not be easy and thus productivity may be reduced.
Therefore, there is a need to develop a method for welding a battery module and a welded structure which may be stable against vibrations and external shocks and may implement an easy operation.
The related art for solving the above problems as described above is disclosed in Korean Patent No. 0760754.